Paper making process utilizing modified locust bean gum



Patented July 7, 1953 PAPER MAKING PROCESS UTILIZING MODI FIED LOCUST BEAN GUM Nat ll'risch, White Plains, and Frank J. Sweeney, Forest Hills, N. Y., a.ssignors to Stein, Hall & Company, Inc., New York, N. Y., a corporation of New York No firawing. A pplication June 26, 1951,

7 Serial No. 233,696

3 claims. (01. 92-21) The present invention relates to an improve-- ment in the process of making paper.

This application is a continuation-impart of agfication Serial No. 65,717, filed December 16,

Many attempts have been made mule past to speed up the paper making process and to increase the strength of the paper formed thereby. Thus, for example, it has been proposed to incorporate into the paper stock locust bean gum or flour prepared from the seed endbsperm of the locust or carob tree (Crdtonia siliizil'a) a perennial legume native to the Mediterranean regmn, The fruit of this tree is in the form of pods. It was known to the ancients as manna and in later periods has been known as St. J ohnsbread. The gum powder generally'known as locust bean gum is obtained from the seeds in these pods and has been utilized heretofore as a film forming material in textile sizing and as 'a thickening agent in printing and dyeing. I

It is known that the addition of locust bean gum to paper stock will result in paper having improved wet and dry strength characteristics. The use of locust bean gum in the manufacture of paper has, however, been discouraged dueto the considerable difficulty involved in uniformly distributing the locust bean gum throughout the aqueous furnish. Even when special equipment in the form of injectors and high speed stirrers is used and the locust bean gum is added slowly to water, an appreciable proportion of the locust bean gum will remain in the form of lumps even after cooking. If these lumps get into the sheet they cause fisheyes and later cause a breakdown in the sheet. Special equipment must therefore be untilized to strain out these lumps, which incidentally result in a waste of locust bean gum, and the tanks in which the gum is mixed and cooked must frequently be drained and cleaned. The additional equipment required and the precautions that must be followed in order to incorporate locust bean gum in paper stock have substantially offset the advantages obtained by use of the gum with the result that the use of locust bean gum in the paper industry has not become widespread.

It has now been found that conventional paper making operations can be materially improved by adding to the aqueous suspension of fibers, normally referred to as the furnish, at a point after all operations designed to substantially modify the fibrous constituents by' mechanical means are completed and prior to the formation of the web,

1, e., preferably at the head box, fan or.

' to drain from the web during passage over the 2 stock regulator box,- an aqueous solution of a combination of locust bean gum, a sodium borate and an acid material selected from the group consisting of glyoxal, pyruvic aldehyde, ammonium chloride, citric acid, boric acid and aluminum sulfate prepared preferably by the cooking operations subsequently disclosed. This method avoids the diificulties involved in adding straight locust bean gum to the furnish, significantly improves the paper making process and results in improving the characteristics of the paper produced r The aqueous solution of a combination of locust bean gum, borate and an acid material can be prepared with utmost facility in any one of a nurn ber of ways. A dry mixture of locust bean gum, borate and acid material may be dispersed readily in cold Water or a dry mixture of locust bean gum and borate may first be dispersed in cold water and the acid material added to the aque ous dispersion so formed. Neither of these methods results in the formation of objectionable lumps and the complete dispersion of the materials can be accomplished in a matter of seconds.

The dispersion is then cooked at an elevated temperature of the order of about F. to 212 F., preferably about 200 F. to open, swe1l or gelatinize the locust bean gum and thereby form a clear and viscous aqueous solution.

Tests have shown that in a sheet into which thismaterial has been incorporated, an improvement in formation results, and also that the addition of the material of this invention results in a general improvement in the quality of paper produced from a given stock. The utilization of this invention, for example, has made it possible to in crease the capacity of a mill having limited drying facilities without reduction in salient properties by making it possible to use stock of increased free ness thereby permitting a greater amount of water wire prior to drying. Also the capacity of a mill to produce a uniformly good quality paper has been increased in View of the improved web for mation from mediocre or poor stock. Thus, for example, it has been found that the method of adding a combination of locust bean gum, borate and acid material to the furnish makes it possible to reduce the proportion of relatively expensive sulfite pulp and increase the proportion of relatively inexpensive groundwood without deleteriously affecting the characteristics of the paper produced thereby or slowing down the speed of the 'w'eb. Normally such standard final quality could be obtained only by a relatively slow operation. In connection with mill operations having good drying capacity and utilizing relatively good starting stock, it has been found that lower drying temperatures or increased speeds are possible with attendant" savings while attaining the same or greater amount of production and the same or ii'ilproved quality of final product.

Changes in the proportions of the critical ingredients used in able effect upon the results obtained in so far as handling and dispersibility are concerned. As the proportion of locust bean gum in the combine tion is decreased, the ease with which it canbe dispersed in water is increased. On the other hand, as proportion of locust bean gum in the combination approaches 109%, it'becomes more difiicult to disperse in water and form lumps that must be strained out the addition of the solution to the furnish. practical matter, the 50% locust bean gum in the combination is too little to obtain the full benefits derived from.

its use and the presence of more than about 96% of the gum will result in sufficient dispersing difificulties to make itsuse uneconom cal. It generally preferred therefore to limit e propor tion of locust bean gum in the combinationto between about 65% and 93%. Optimum results have been obtained with'concentrations of between 85% and 90%. 7

Changes in the relative proportions of borate and acid material also have a considerable effect upon the results obtained in the paper making operation and more sistency and characteristics in the aqueous solu tion formed when the combination is added to water and cooked. The borate tends to impart to the cooked solution a heavy body, high film strength and stringiness. The acid re duces the ropiness of the cooked solution; parts a long stringy character thereto and reduces its viscosity to a level that makes handling of the solution practicable.

It has generally been found desirable to adjust the relative proportions of locust bean'gum, borate and acid material so'that the dispersion thereof in water before cooking or the solution thereof after cooking will have a pH between about 3 and 10. The lower limit of the pH range is determined by the characteristics of the particular locust bean gum. in the combination and particularly by its ability to open or become gelatinized when cooked. If the pH is reduced to a value below about 3, it becomes extremely difficult, and in some cases impossible, to gelatinize the locust bean gum by cooking. The upper limit of the pH range is determined by the viscosity of the cooked solution. It is essential in practice that the cooked solution be not so viscous that it cannot readily be transthe combination have considermore liable to particularly upon the con-' presence of less than about ferred from a cooking vessel to a supply vessel or the head box, fan pump or stock regulator box. Reduction of the viscosity simply by diluting the solution with water is not practicable because that would involve increasing the capacity of the cooking vessel or supply tan and of the pumping equipment utilized to add the cooked solution to the furnish. therefore to maintain the pH between about and 10 so that the cooked solution will not be too viscous and at the same time not too acid to prevent or inhibit gelatinization of the locust bean gum. While it is possible to carry out the process of this invention at either extreme pl-I value, it has been found that optimum results are obtained by maintaining the pH at about 8.0 to 8.2. Within this more limited range, the locust bean gum will from a supply vessel to It is preferable few seconds, however,

manner in as little .as' 9.6 seconds.

become gelatinized quite readily and the viscosity of the cooked solution is sufiiciently low to permit easy transference of the cooked solution from supply source to the head box, stock regulator box, fan pump, or to any other point at w ich the combination is added to the furnish. Satisfactory viscosity and gelatinisation conditions are normally obtained by maintaining the ratio of borate toacid material at between about 1:1 and 3:1 and preferably at about 2:1.

, A mixture that has been found to be particu-. larly successful is one containing 85% by weight of locust bean gum, 10% by Weight of borate and 5% by weight of acid material. When a hand" ful of this mixture is simply dumped into cold water, it at first floats on the surface. Within a the mass of material breaks up into smaller portions which fall to the bottom until all of it has left the surface of the water- Simple stir ing of, the water willthereuponform a uniform dispersion of the material which, upon being cooked to a t 'perature of about 209 F., will form a viscous, stringy and. transparent solution.

By way of contrast, when straight locust bean gumis dumped into cold water, only a small portion of it may fall to the bottom. of the locust bean gum remains floating on the. surface. The outer portions of the mass appar: ently absorb water, swell andbecome sticky so as to form a coating that, denies access of water to the interiorjofthe mass. Vigorous stirring' fails to produce a uniform distribution'of the gum throughout the water and cooking thereof.

concentrations of locust bean gum that are less than about starch maybe added to make up for'the lack of locust bean gum. Thus, for example, favorable results have been obtained with a mixture consisting of 68% gum, 17% starch, 10% borate and 5% acid mateial. Small amounts of oxidizing agents, such as barium peroxide and sodium perborate may be added to thin out the solution prepared when the combination is dissolved inwater.

The borate may be any suitable borate such as, for example, sodium tetraborate (borax) and sodium metaborate. I

The acid material may be glyoxal, pyruvic aldehyde, ammonium chloride, citric acid, boric acid or aluminum sulfate or a combination of one or more of said materials. The presence of. glyoxal or ammonium chloride in the combination is particularly desirable because they both promote an extremely rapid and facile dispersion or" the mixture in cold water. A mixture consisting of locust bean gum, 11 borax and 5% glyoxal, for example, will readily and completely disperse in water at room temperature in as little '7 If ammonium chloride is ca instead of the glyoxal, the mixture will disperse under the same conditions and in the same Glyoxal therefore is preferable from the standpoint of rapidity of dispersion whereas ammonium chloride is preferable from the standpoint of economy inasmuch as the price or" ammonium chloride is much lower than that of glyoxal.

Aqueous solutions containing from about A up to about 5% by weight of solute may readily be prepared.

In accordance with the preferred practicejaand most locust bean 1%. solution of the mixture is made by adding it, in the form of a dry powdento onev half the required amount of water while the water is cold, then cooking to 200 F; and finally adding the remaining water required to produce a 1% solution. This solution is then. added to the pulp in the head box, at the fan pump or in thev regulator box at a rate suflicient to add. from about 1 to 20 or 30.1bs, of the mixture, based on the dry weight thereof, to a. ton. of furnish, likewise based on the dry weight thereof, As in ordinary paper making. processes, the concentrated stock, consisting of a maximum. of approximately 4% solids, is diluted at the fan pump to a much more dilute state, e. g., 0.5%

The addition of a solution of locust beangum, boraterand acid material'to a paper stock permits increasing the freeness of the stock, reducing the power consumption in the refining phases and. the steam consumption in. the dryer section, all. of which makes possible an increase in the speed at which the paper is. run oil; and. generally improves. the characteristics of the paper produced at a given set of machine conditions.

A number of typical formulae are listed in the tables below, the. numerals therein referring to percentages by weight.

the. concentration of solids down to: 1% by weight. 7 The temperature of. these solutions was maintained at about 180 F. v

A 1% solution of locust bean gum alone was prepared in a. similar manner. I A. number of paper making runs, on a. laboratory scale, corresponding to the number of. solutions prepared, were then made. in each run, one of the prepared solutions was added to the furnish at :a rate of 10 lbs., based-on the dry weight, of solution to a ton of furnish, likewise based on the dry weight.

Two sheets each having a weight of 2.8 grams were selected from each run to eliminate test errors due to variations in the Weight of the sheets produced and each sheet selected wassubjected to ten mullen tests. The averages of the twenty mullen tests in each run are tabulated below:

Formula No.

TABLE 1.

Formula No 1 2 3 4 5 6 7 8 9 10 11 87 90 90 85' 85 8O 70 60 84 7' 5 6 10' 10 12 20 26. 6 33. 3 11' G1yoxa1 5 6; 5 4. 5 5 5 Pyruvic Aldehyde v 5 2 Ammonium Chloride 5 3 5 8.4 11.7 3

TABLE 2 Formula No a... 12- 13 14 15 16 17 18 19 20 21 Locust Bean. Gum 84. 9. 85 85 84 85 Powdered Potato Starch .ii. 17

In order to further illustrate the invention without, however, intending to limit its scope thereto, the following examples are included.

Example 1 Four batches of locust bean gum, borax and glyoxal, corresponding to formulae Nos 1, 2, 3,

and 4 of Table 1, were made up on a laboratory scale. A 1% aqueous solution of each batch was formed by dispersing one part by weight of the. dry mixture in about 50 parts by weight of water, cooking the resulting" dispersion tov 200 F. and

then adding sufli'cient" additional water to bring.

Example 2 Dry mixtures corresponding to formulae Nos. 7, 8, 9, 10, 11, 13, 14, 16, 18, 19 and 20 were made up, on a laboratory scale into 1% aqueous solutions by dispersing one part by weight of each dry mixture in about 50 parts by weight of water, cooking the resulting dispersions to 200 F. and then adding sufiicient'additional water to bringv the concentration of solids down to 1% by weight. The temperature of these solutions was. main-.- tained at about 180 F.

A number of paper. making runs on a labora-- tory scale were. then made; In each run, a num-.- ber of blank and modified paper sheets weremade. The'blank sheets were made without adding, a locust bean gum containing solution to: the furnish and the modified sheets were made: by adding one of the prepared solutions at a rate of 10 lbs;,, basedv on the dry weight, of solution. to a ton of furnish, likewise based on? the dry Weight. 1

Formula No. 7 Sheets Example 3 Dry mixtures corresponding to formulae Nos. 12 and 21 were made up, on a laboratory scale into 1% aqueous solutions by dispersing one part.

' tory scale were then made. In each run, a number of blank and modified paper sheets were made. The blank sheets were made without adding a locust bean gum containing solution to the furnish and the modified sheets were made by" adding one of the cooked solutions, at a temperature of approximately 100 F. and at a rate of lbs., based on the dry weight, of solution to a ton of furnish, likewise based on the dry weight.

Two blank sheets and two modified sheets each having a weight of 2.97 plus or minus .03 gram were selected from each run to eliminate test errors due to variations in the weight of the sheets produced and each sheet selected was subjected to ten mullen tests. The averages of the twenty mullen tests conducted on each set of two sheets are tabulated below:

Modified Sheets Blank Example 4 Dry mixtures corresponding to formulae Nos. 22, 23 and 24 were made up, on a laboratory scale, into 1% aqueous solutions by dispersing one part by weight ofeach dry mixture in about 50 parts by weight of water, cooking the resulting dispersions to 200 'F. and then adding sufficient additional wate'r to bring the concentration of solids downto 1 %'by weight.

A number of blank and modified paper's'heets were made and'tested in the mannerdescribed in Example 3; In addition, modified sheets were made by adding the prepared solution at a rate of 5 lbs., based on the dry Weight, of solution to a ton of furnish, likewise based on the dry weight. These modified sheetswere likewise subjected to mullen tests. 2: 3 7

Two blank sheets and two modified sheets, each having a weight of 3.0 plus or minus .01

grams were selected from each run to eliminate 8. test errors due, to variations in the weight of the sheets produced and each sheet selected was subjected to ten mullen tests The average of the twenty mullen tests conducted on each set of two, sheets and the increases in per cent mullen obtained with the modified sheets are tabulated immediately below:

It is to be understood that innumerable modifications will readily occur to those skilled in the art upon reading this description. All such modifications are intended to be included within the scope of the present invention as defined in the appended claims. We claim: 1. In a process of making paper from an aqueous suspension of fibrous material, the step which comprises adding, to said suspension, after all operations designed to substantially modify the fibrous constituents by mechanical means are completed and prior to the formation of the Web, an aqueous solution of a cooked mixture of locust bean gum, a sodium borate and a salt selected from the group consisting of ammonium chloride and aluminum sulfate, the gum being present in the mixture in an amout from at least about equal to the combined weight of borate and salt to about 96% of the mixture, the relative proportions of the borate to the salt ranging from about 3:1 to 1:1 by weight, and the amount of cooked mixture of gum, borate and salt in the solution ranging from an appreciable amount up to about 30 lbs. per ton of based on the dry weight thereof.

2. In av process of making paper from an aquefibrous material in the aqueous suspension, both ous suspension of fibrous material, the step which comprises adding, to said suspension, after all operations designed to substantially modify ammonium chloride and aluminum sulfate, the

amount of cooked mixture of gum, borate and salt in the solution ranging from an appreciable amount up to about 30 lbs. per ton of fibrous material in the aqueous suspension, both based on the dry weight thereof.

3. In a process of making paper from an aqueous suspension of fibrous material, the step which comprises adding, to said suspension, after all operations designed to substantially modify the fibrous constituents by mechanical means are completed and prior to the formation of the web, an aqueous solution of a cooked mixture con.- taining from to parts by weight of locust bean gum, from 5 to 10 parts by weight of a sodium borate and from 2 to 6 parts by weight of a salt selected from the group consisting of ammonium chloride and aluminum sulfate, the

2 Number amount of cooked mixture of gum, borate and salt in the solution ranging from an appreciable amount up to about 30 lbs. per ton of fibrous material in the aqueous suspension, both based on the dry weight thereof.

NAT FRISCH.

FRANK J. SWEENEYQ References Cited in the file of this patent UNITED STATES PATENTS Name Date 60,635 Irving et a1. Dec. 18, 1866 1,106,335 Pinel Aug. 4, 1914 1,280,861 Satow Oct. 8, 1918 1,334,356 Dunham Mar. 23, 1920 1,448,847 Kaiser Mar. 20, 1923 1,839,346 Seferiadis Jan. 5, 1932 Broadbent et a1., Tech. Supplement to Worlds Paper Trade, Review, June 27, 1941, pp. 49-56.

Mason, Chemical Industries, January 1944, pp. I

66and 67.

The Determination of Hydrogen Ion by Clark, published by Williams and Wilkins 00., Baltimore, Md. (1927), chapter 6 particularly pp. 108, 110 and 112-117. 9 

3. IN A PROCESS OF MAKING PAPER FROM AN AQUEOUS SUSPENSION OF FIBROUS MATERIAL, THE STEP WHICH COMPRISESS ADDING, TO SAID SUSPENSION, AFTER ALL OPERATIONS DESIGNED TO SUBSTANTIALLY MODIFY THE FIRBOUS CONSTITUENTS BY MECHANICAL MEANS ARE COMPLETED AND PRIOR TO THE FORMATION OF THE WEB, AN AQUEOUS SOLUTION OF A COOKED MIXTURE CONTAINING FROM 85 TO 90 PARTS BY WEIGHT OF LOCUST BEAN GUM, FROM 5 TO 10 PARTS BY WEIGHT OF A SODIUM BORATE AND FROM 2 TO 6 PARTS BY WEIGHT OF A SALT SELECTED FROM THE GROUP CONSISTING OF AMMONIUM CHLORIDE AND ALUMINUM SULFATE, THE AMOUNT OF COOKED MIXTURE OF GUM, BORAGE AND SALT IN THE SOLUTION RANGING FROM AN APPRECIABLE AMOUNT UP TO ABOUT 30 LBS. PER TON OF FIBROUS MATERIAL IN THE AQUEOUS SUSPENSION, BOTH BASED ON THE DRY WEIGHT THEREOF. 